In a gas turbine, gas is typically produced by the combustion of fuel. The gas is then passed over a collection of stationary nozzles, which discharge jets of gas against the blades of a turbine rotor, forcing the rotor to rotate. The rotation of the rotor drives the external load of the turbine, such as an electrical generator.
One problem with gas turbines is that the gas loading on the nozzles and the high temperatures in the turbine, eventually cause the stationary turbine nozzles to deform. This is a particular problem with turbines where the nozzles are made of cobalt-based superalloys and use a cantilevered design.